Simplify the following expression: $r = \dfrac{-4t + 9}{2t - 10} \div \dfrac{1}{4}$
Dividing by a number is the same as multiplying by its inverse. $r = \dfrac{-4t + 9}{2t - 10} \times \dfrac{4}{1}$ When multiplying fractions, we multiply the numerators and the denominators. $r = \dfrac{(-4t + 9) \times 4} {(2t - 10) \times 1}$ $r = \dfrac{-16t + 36}{2t - 10}$ Simplify: $r = \dfrac{-8t + 18}{t - 5}$